There are seven different species of turtle in the world, six of which nest in Mexico.

But it is the leatherback which appears to be most at risk, although some specialists are hopeful that their numbers could start to recover between the next five to 10 years.

Plastic bags

Leatherbacks can grow up to 2.5m long and weigh almost a ton. They have a leathery shell and live on jellyfish.

There are thought to be many reasons why the turtle numbers are down. Most of these are blamed on humans including the fact that many die every year from swallowing plastic bags which float into the sea.